Microcantilever with integral self-aligned sharp tetrahedral tip

A method of forming a microfabricated cantilever with a single crystal, integral silicon tip, comprising the steps of:

• providing a (100) silicon wafer having a front side and a rear side;
• anisotropically etching the rear side of the silicon wafer to form a silicon membrane in said silicon wafer;
• forming a layer of cantilever material on the front side of the silicon membrane and a layer of cantilever material on the rear side of the silicon membrane to form a sandwich structure;
• patterning and etching the sandwich structure to remove portions of the silicon membrane and the two layers to form a cantilever structure and to expose sidewall portions of the silicon membrane;
• oxidizing the exposed sidewall portions of the silicon membrane to form oxide sidewalls;
• selectively removing the layer on the front side of the cantilever structure, to expose the front side of the silicon membrane;
• anisotropically etching the exposed front side of the silicon membrane to remove said silicon membrane except for a tetrahedral silicon tip form on the rear side of the nitride layer, said tetrahedral silicon tip having one exterior surface bounded by a (111) plane, said tetrahedral tip having two additional exterior surfaces bounded by the oxide sidewall;
• and
• removing the oxide sidewall to provide a cantilever formed from the rearside cantilever-material layer and having a tetrahedral silicon tip at the free end thereof.

A microfabricated cantilever with an integral tip, comprising:

• a silicon base formed from a (100) silicon wafer, said silicon base having a top surface and a parallel bottom surface formed in (100) crystal planes, said silicon base also having an obliquely extending lateral edge surface formed in the (111) plane;
• a layer of nitride covering the obliquely extending lateral edge surface, said layer of nitride having a cantilever portion extending outwardly in the direction of the (100) crystal planes from the top surface of the silicon base, said cantilever portion having a free end;
• and
• a tetrahedral silicon tip formed on the free end of the cantilever portion of the layer of nitride, said tetrahedral silicon tip having one exterior surface bounded by a (111) plane, said tetrahedral silicon tip having two additional exterior surfaces bounded by planes extending perpendicularly to the cantilever portion of the layer of nitride.